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<br />1, at the northeast corner of the project site, had an Leq-15min of 63 dBA and a Lmax of 81 dBA, attributed to train
<br />horns; ST-2, at the southeast corner of the project site, had an Leq-15min of 65 dBA and a Lmax of 81 dBA, attributed
<br />to train horns; ST-3, at the southwest corner of the project site, had an Leq-15min of 69 dBA and a Lmax of 74 dBA,
<br />attributed to traffic along El Camino Real; and ST-4, at the northwest corner of the project site, had an Leq-15min of
<br />71 dBA and a Lmax of 80 dBA, attributed to bus stop activities such as engine revving, bus lowering, warning signal
<br />beeping, etc.
<br />Construction Noise (Illingworth & Rodkin, pp. 23-27): Construction of the Commercial Component is expected to
<br />occur over an approximately 26-month period anticipated to start mid-August 2025 and be completed in early
<br />November 2027, with construction hours planned for 7:00 AM to 7:00 PM, Monday through Friday. Construction
<br />activities will vary based on the type of equipment used, the process, and the location. Construction activities are
<br />typically carried out in phases with each phase comprised of a different mix of equipment; noise levels would naturally
<br />vary by phase and within phases, depending on the amount of equipment in operation and the location of the equipment
<br />operating. The loudest noise levels are typically from demolition, grading/excavation, trenching/foundations, concrete
<br />work, and crane work. These activities would be expected to use concrete/industrial saws, excavators, rubber-tired
<br />dozers, tractors, loaders, backhoes, graders, and a crane, but would not include pile driving. At 50 feet from the
<br />construction noise source, the range of maximum instantaneous equipment noise levels for the proposed Commercial
<br />Component would be approximately 70 to 90 dBA Lmax, with hourly average noise level ranging from about 75 to 89
<br />dBA Leq for typical construction activities related to life-science R&D and office buildings, without mitigation. It is
<br />important to note that noise levels attenuate with distance; e.g., construction-generated noise levels drop off at a rate
<br />of about 6 dBA per doubling of the distance between the source and receptor. In addition, buildings and/or terrain
<br />often provide shielding effects that result in lower noise levels. These noise levels would be expected to meet the
<br />Municipal Code criterion of 110 dB or below at the nearest residences.
<br />As discussed in the Illingworth & Rodkin noise study (pp. 23-24), Chapter 24 of the Redwood City Municipal Code
<br />limits construction activities within 500 feet of a residential district to between 7:00 AM and 8:00 PM on weekdays,
<br />with no construction allowed on weekends and holidays, within 500 feet of a residential district. For construction
<br />within residential districts, the Municipal Code additionally limits noise to 110 dBA and limits noise from individual
<br />pieces of construction equipment to 110 dBA at a distance of 25 feet within a residential district. Because the proposed
<br />Commercial Component site is not located within a residential district, the Illingworth & Rodkin study concluded that
<br />these thresholds would not apply, and therefore Illingworth & Rodkin relied on noise limits established by the Federal
<br />Transit Administration (FTA). These FTA noise limits, identified in the FTA Transit Noise and Vibration Impact
<br />Assessment Manual, establish an exterior daytime noise threshold of 80 dBA Leq for the nearest residential uses, which
<br />are located about 185 feet southwest of the project component site, as well as Sequoia High School across El Camino
<br />Real. For the nearest commercial land uses, including the train station nearby, an exterior daytime noise threshold
<br />would be 85 dBA Leq, per the FTA manual.
<br />Illingworth & Rodkin (pp. 24-27) projected noise during each construction phase based on the two loudest pieces of
<br />construction equipment for each construction phase at 50 feet, per FTA recommendation. Temporary construction
<br />noise was also assessed at the receiving property lines of all existing receptors in the area that would have direct
<br />exposure to the project component site, and the hourly average noise levels included all construction equipment
<br />operating simultaneously in each phase for the R&D/office building, with no reductions assumed due to intervening
<br />buildings or existing barriers.
<br />Construction Noise Conclusion. Illingworth & Rodkin determined (p. 27) that construction noise levels at a distance
<br />of 50 feet would range intermittently from 74 to 84 dBA Leq, with noise levels adjusted for actual distances from the
<br />project building ranging from 56 to 73 dBA Leq at the high school and nearest residence, and from 55 to 77 dBA Leq
<br />at surrounding commercial uses and the train station. Because these construction noise levels would not exceed the
<br />exterior FTA thresholds of 85 dBA Leq at office and commercial land uses or 80 dBA Leq at residential land uses in
<br />the Commercial Component vicinity, this impact would be less than significant.
<br />As identified in SEIR Mitigation Measure NO-1, implementation of the following standard regulations would be
<br />required as part of the Commercial Component’s conditions of approval and would further reduce the less than
<br />significant noise impact:
<br />1. Construction Plan. Prepare a detailed construction plan identifying the schedule for major noise-generating
<br />construction activities. The construction plan shall identify a procedure for coordination with nearby noise-sensitive
<br />facilities so that construction activities and the event schedule can be scheduled to minimize noise disturbance. This
<br />plan shall be provided to all noise-sensitive land uses within 500 feet of the construction site.
<br />ATTY/RESO.0031/CC RESO CEQA GUIDELINES (901 EL CAMINO REAL)
<br />REV: 04-22-25 VR
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